Issue 26044. Cache and use LibraryElementImpl.exportNamespace.

pkg/analyzer/lib/src/generated/incremental_resolver.dart

Index: pkg/analyzer/lib/src/generated/incremental_resolver.dart
diff --git a/pkg/analyzer/lib/src/generated/incremental_resolver.dart b/pkg/analyzer/lib/src/generated/incremental_resolver.dart
index 9f4e41939e59f2d3603ee4fe6452943b01a72071..6e5396533ad429b6bfe14af211f1906aaedda595 100644
--- a/pkg/analyzer/lib/src/generated/incremental_resolver.dart
+++ b/pkg/analyzer/lib/src/generated/incremental_resolver.dart
@@ -878,7 +878,7 @@ class IncrementalBodyDelta extends Delta {
 
   @override
   DeltaResult validate(InternalAnalysisContext context, AnalysisTarget target,
-      ResultDescriptor descriptor) {
+      ResultDescriptor descriptor, CacheState state, Object value) {
     // A body change delta should never leak outside its source.
     // It can cause invalidation of results (e.g. hints) in other sources,
     // but only when a result in the updated source is INVALIDATE_NO_DELTA.